Most generally available barrier assemblies provide some sort of coupling between the barrier and the barrier operator mechanism that is intended to perform at least one of the following functions: to protect the barrier operator mechanism from being damaged by a mechanical overload; and to allow disconnection of the barrier from the barrier operator in the event manual movement of the barrier is needed.
It is not uncommon for barriers to encounter obstructions or be hit by vehicles. Swing gate operators, for instance are particularly susceptible to damage from vehicles. Conventional hinged swing gate installations include a gate connected via linkage to an operator that opens and closes the gate. When an object, such as a vehicle, hits a swing gate, very large torques can be generated at the operator's output shaft by way of the force imparted on crank arm, which can result in damage to the operator.
The current state of the art in coupling of an operator to crank arms on barrier operators is shown in FIGS. 1-3. Referring to FIGS. 1-3, a barrier operator has a barrier operator coupling 100 that consists of a journal 110, which is attached to a gearbox 111, a crank arm 112, clamp halves 113 and 116, a bolt 114, and a release handle 115. The assembly of clamp halves 113 and 116 is releasably mountable on the journal 110 with the bolt 114. The release handle 115 is attached to the clamp halves 113 and 116 and configured to move the clamp halves toward and away from each other to form an adjustable clamp 117 that attaches to the journal 110 (as shown, e.g., in FIG. 4). By adjusting the release handle 115, it is possible to adjust the tightness of the bolt 114, which in turn adjusts the tightness of the clamp 117. Further, it is possible to loosen the release handle 115 and manually open the barrier if required. In addition, barriers can vary widely in their weight and length or width. Because the rate at which the barrier can be accelerated is dependent on the inertia of the barrier, barrier operators are typically designed to accommodate the largest inertial load they are specified to accommodate. This leads to sub-optimal motion where smaller, lighter barriers are moved, or compromised operator life where barriers at the limits of specification are moved.